Chapter 1: Introduction Classification of Matter Matter can exist in different forms or phases: (1) States of Matter solidliquidgas

Chapter 1: Introduction Classification of Matter solid liquid gas

Chapter 1: Introduction Classification of Matter Solid Liquid Gas Defined shape? Defined volume? Distance between molecules? Compressible? Yes No Yes No Small intermediate large No Yes

Chapter 1: Introduction Classification of Matter (2) Molecules, Elements, Compounds, Pure Substances, and Mixtures Molecules: → contain more than one atom → atoms may be the same or different types atom

Chapter 1: Introduction Classification of Matter Elements: → contains one unique kind or atom → may consist of atoms or molecules (2) Molecules, Elements, Compounds, Pure Substances, and Mixtures

Chapter 1: Introduction Classification of Matter Compounds: → composed of two or more elements → contain more than one type of atom (2) Molecules, Elements, Compounds, Pure Substances, and Mixtures

Chapter 1: Introduction Classification of Matter Pure Substance: → has distinct properties → can be element or compound (2) Molecules, Elements, Compounds, Pure Substances, and Mixtures

Chapter 1: Introduction Classification of Matter Mixtures: → properties vary between samples → contain different substances (2) Molecules, Elements, Compounds, Pure Substances, and Mixtures

Chapter 1: Introduction Classification of Matter Homogeneous Mixtures Heterogeneous Mixtures (2) Molecules, Elements, Compounds, Pure Substances, and Mixtures → uniform → solutions (solid, liquid, gas) Air Oil on water

Chapter 1: Introduction Homogenous or Heterogeneous Mixtures? Granite Mud Coffee - a heterogeneous homogeneous Coffee - b heterogeneous Water and flour heterogeneous Vinaigrette heterogeneous Brass homogeneous

Chapter 1: Introduction

Classification of Matter (2) Molecules, Elements, Compounds, Pure Substances, and Mixtures Molecules or atoms? MoleculesAtoms Molecules and atoms Compound?yesno Phase state?gassolid and gassolidgas Mixture? - what kind? noyes - heterogeneous homogeneous

Chapter 1: Introduction Mixtures can be separated Filtration Distillation Chromatography... for example by

Chapter 1: Introduction Properties of Matter Physical Properties & Changes Chemical Properties & Changes → no change in identity or composition of substance → how a substance reacts to form a different substance

Chapter 1: Introduction Properties of Matter Melting of ice: Physical process phase changes but it's still H 2 O Burning of wood: Chemical process conversion to CO 2 and H 2 O

Chapter 1: Introduction Physical of Chemical Property? Zinc (Zn): silver-grey metal melting point: 420 o C generates hydrogen when dissolved in sulfuric acid density (25 o C) = 7.13 g/cm 3 reacts with oxygen to form Zinc oxide (ZnO) Physical property Chemical property Physical property Chemical property

Chapter 1: Introduction Physical or Chemical Process? Sugar dissolving in water.Physical process a) compounds in the gas phase b) elements in the gas phase c) molecules in the gas phase d) a heterogeneous mixture of elements e) a mixture of molecules in the liquid phase The picture on the left represents

Chapter 1: Introduction Intensive Properties… …are independent of the amount of substance Extensive Properties… …depend on the amount of substance Boiling/melting point (bp/mp) Mass Volume Density Intensive property Extensive property Intensive property

Chapter 1: Introduction A gold nugget (1 cm x 0.5 cm x 0.7 cm) has a density of 19.3 g/cm 3. A jeweler decides to use this gold nugget to make a perfect gold sphere with a diameter of 0.4 cm. What is the density of this sphere? Density is an intensive property which is independent of quantity. The density of gold is independent of shape or size: 19.3 g/cm 3

Chapter 1: Introduction Units of Measurement: Temperature K = O C + 273

Chapter 1: Introduction Units of Measurement Système International d'Unités (SI units) Masskilogramkg Lengthmeterm Timeseconds TemperatureKelvinK Amount of a substancemolemol

Chapter 1: Introduction Units of Measurement Prefixes used in the metric system: You ABSOLUTELY MUST know these (Table 1.5 page 14): GigaGgigameter (Gm) = 10 9 m MegaMmegameter (Mm) = 10 6 m KiloKkilometer (Km)= 10 3 m meter (m)= 1 m Deciddecimeter (dm)= m Centiccentimeter (cm)= m Millimmillimeter (mm)= m Microµmicrometer (µm)= m Nanonnanometer (nm)= m Picoppicometer (pm)= m Femtoffemtometer(fm)= m

Chapter 1: Introduction Units of Measurement: Derived Units Volume: 1m (1 m) 3 = 1m 3 = 1cubic meter 1cm (1 cm) 3 = 1cm 3 = 1cubic centimeter = 1mL

Chapter 1: Introduction Dimensional Analysis Converting inches into cm: - the units to be eliminated go on opposite sides of the fraction Conversion factor: same quantity but in different units Converting m/min into m/s: Conversion factor

Chapter 1: Introduction Dimensional Analysis More than one conversion: A car travels 12 km per liter of gasoline. How many miles per gallon will it go? =>Convert 12 km/L into mi/gallon (1) or (2) =>first, convert length units: km into mi, second, convert volume units: L into gallons

Chapter 1: Introduction Dimensional Analysis More than one conversion: A car travels 12 km per liter of gasoline. How many miles per gallon will it go? =>Convert 12 km/L into mi/gallon (1) (2) Correct number of sig. figs. =>first, convert length units: km into mi, second, convert volume units: L into gallons

Chapter 1: Introduction Dimensional Analysis More than one conversion: A car travels 12 km per liter of gasoline. How many miles per gallon will it go? =>Convert 12 km/L into mi/gallon =>first, convert length units: km into mi, second, convert volume units: L into gallons => with more PRACTICE you can combine steps (1) and (2):

Chapter 1: Introduction Dimensional Analysis Conversions involving squared and cubic units: The volume of a container is 5.3 m 3. What is the volume in cm 3 ? =>Convert m 3 into cm 3 Units must match in order to cancel out!

Chapter 1: Introduction Dimensional Analysis Conversions involving squared and cubic units: The volume of a container is 5.3 m 3. What is the volume in cm 3 ? =>Convert m 3 into cm 3 Units must match = cube both number AND unit !

Chapter 1: Introduction Uncertainty in Measurement Inexact Numbers Exact Numbers Obtained by measurement Value is known precisely The temperature of the asphalt on Randall Drive today? The number of mm in one yd of speaker cable ? Mass of 1L of milk? inexact exact

Chapter 1: Introduction Uncertainty in Measurement good accuracy good precision poor accuracy good precision poor accuracy poor precision good accuracy poor precision Accuracy: how do the measured values agree with the “true” value? Precision: how reproducible is the measurement?

Chapter 1: Introduction Significant Figures Which digits count? 1. All significant digits in a number Zeros... (a)...between nonzero digits count (b)...in the beginning of a number never count (c)...at the end of a number....??? sig figs sig figs 1.32 sig figs sig figs

Chapter 1: Introduction Significant Figures g 2.03 g 4 significant figures3 significant figures

Chapter 1: Introduction Significant Figures g g 4 significant figures

Chapter 1: Introduction Significant Figures If you don’t know where the number comes from, the number of significant figures is ambiguous: 51,000 mg

Chapter 1: Introduction Significant Figures To eliminate ambiguity, express your number in scientific notation: 51,000 mg 5.1 x 10 mg x 10 mg 4 2 significant figures 5 significant figures

Chapter 1: Introduction Significant Figures OK, but how many significant figures does the number 51,000 have? 51,000 mg By convention (IUPAC): 51,000 mg = Zeros... (c)...at the end of a number do NOT count 5.1 x 10 mg 4 2 significant figures

Chapter 1: Introduction Significant Figures sig figs sig figs sig figs 45,0002 sig figs In exponential notation: = x 0.01 = x = x 0.1 = x ,000 = x = x 10 4

Chapter 1: Introduction Significant Figures Final result is only as accurate as the least accurate measurement The least accurate measurement determines the number of sig. figs. (1) Division and Multiplication: volume = 1.32cm x 1.1cm x 3.540cm = cm 3 = 5.1cm 3 velocity = 342 m / 32 s = m/s = 11 m/s Number with fewest sig. figs. determines sig. figs. of answer Answer rounded to 2 sig. figs.

Chapter 1: Introduction Significant Figures Final result is only as accurate as the least accurate measurement The least accurate measurement determines the number of sig. figs. (2) Addition and Subtraction = Number with fewest decimal places (NOT sig. Figs.) determines answer = answer rounded to 1 decimal point